Beware that you have to associate only 1 AZ to a node pool or cluster-autoscaler may end up failing to reliably add nodes on demand due to the fact
that what cluster-autoscaler does is to increase/decrease the desired capacity hence it has no way to selectively add node(s) in a desired AZ.

Deploying a node pool powered by Spot Fleet

Utilizing Spot Fleet gives us chances to dramatically reduce cost being spent on EC2 instances powering Kubernetes worker nodes while achieving reasonable availability.
AWS says cost reduction is up to 90% but the cost would slightly vary among instance types and other users' bids.

Spot Fleet support may change in backward-incompatible ways as it is still an experimental feature.
So, please use this feature at your own risk.
However, we'd greatly appreciate your feedbacks because they do accelerate improvements in this area!

It is recommended to temporarily bring up an another, spare node pool to maintain the whole cluster capacity at a certain level while replacing the spot fleet.

Pre-requisites

This feature assumes you already have the IAM role with ARN like "arn:aws:iam::youraccountid:role/aws-ec2-spot-fleet-role" in your own AWS account.
It implies that you've arrived "Spot Requests" in EC2 Dashboard in the AWS console at least once.
See the AWS documentation describing pre-requisites for Spot Fleet for details.